Infiltration cannula

ABSTRACT

An infiltration cannula and method of using the infiltration cannula during an infiltration procedure are disclosed herein. The infiltration cannula includes: a tubular needle and a hub. The tubular needle has a proximal end and a distal end. The tubular needle also has a plurality of apertures disposed in a pattern about the distal end. The apertures are configured to infiltrate fluid into the subcutaneous tissue of a patient. The hub is configured to be held by a person performing the infiltration procedure. The hub has a first end and an opposing second end. The first end is attached to the proximal end of the tubular needle and the second end includes a connector configured to connect to an input source for receiving the fluid to be infiltrated into the subcutaneous tissue of the patient. The fluid flows from the connector, through the hub and into the tubular needle.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of U.S. patent applicationSer. No. 11/646,043 filed on Dec. 27, 2006 now U.S. Pat. No. 7,914,504which is a continuation of U.S. patent application Ser. No. 10/442,370filed on May 21, 2003 now abandoned, the entirety of the disclosures ofwhich are expressly incorporated herein by reference.

STATEMENT RE: FEDERALLY SPONSORED RESEARCH/DEVELOPMENT

Not Applicable

BACKGROUND OF THE INVENTION

The present invention relates in general to cannulas and in particularto an infiltration cannula that allows for intermittent infiltration offluids, such as a local anesthetic.

Many medical procedures require infiltration of fluids, such as a localanesthetic. One method of infiltration of local anesthetic is via aninfiltration cannula. Infiltrators currently on the market are known assprinkler-tip or Klein (the present applicant) needle infiltrators.These cannulas are constructed out of a rigid stainless steel and haveone or more apertures, which are typically round or oval, and aredistributed about the distal end of the cannula. The apertures aredistributed over about 15% to 25% or less than 5.0 cm. of the distal endof the cannula needle. These traditional infiltration cannulas areintended to be inserted through a small incision in the patient's skinand then moved in and out through the subcutaneous tissue while a dilutesolution of local anesthetic (or other pharmaceutical solution) isejected through the distal apertures. Such infiltrators typically have ablunt tip and require the placement of a small hole (made by a one mmskin-biopsy punch or a small surgical blade) through which the blunttipped cannula can be passed. The piston-like in and out motion of thecannula causes the patient discomfort.

Another method of fluid insertion is via a peripherally inserted centralcatheter, also called a PICC line comprising an elongate plastic tubethat is placed inside a vein of the patient. PICC lines are typicallyused for procedures requiring delivery of fluids over a prolonged periodof time. For example, a PICC line may be used when a patient needs toreceive intravenous (IV) fluids, such as medication or nutrients over aprolonged period of time, such as a week or more.

The On-Q® Pain Management System marketed by I-Flow® Corporation employsa PICC line type system for continuously providing local anesthetic.This system provides prolonged local anesthesia by means of an elastomer(elastic container) device that continuously infiltrates a solution oflocal anesthesia over many hours. The On-Q® device is a long softflexible tube with many small holes arranged along a significant portionof the tube. The On-Q® device is designed to be positioned within asurgical wound at the time of surgery; after the surgical wound isclosed the On-Q® device permits slow steady infiltration of a localanesthetic solution into the wound, thereby attenuating post-operativepain. The On-Q® device cannot be inserted through a tiny hole in theskin into subcutaneous tissue. Thus there is a need for a simple devicethat can permit the direct percutaneous insertion of a multi-holedinfiltration cannula into subcutaneous tissue for the localized deliveryof medications such as local anesthetics, chemotherapeutic agents, orcrystalloids for parenteral hydration.

Traditional techniques for subcutaneous injection of local anestheticsolutions use a high-concentration/low-volume of local anesthetic. Thisis associated with a rapid systemic absorption of the local anesthetic.In order to achieve a prolonged local anesthetic effect, the traditionaltechniques for using local anesthetics necessitate either frequentrepeated injections or slow continuous subcutaneous infusion of thelocal anesthetic. As described above, repeated injections or piston-likemovement of the cannula causes patient discomfort. Slow continuousinfiltration may not be desirable in certain situations. Furthermore,continuous infiltrations restrict patient movement for extended periodsof time which also cause the patient discomfort. Thus, there is a needfor a system for infiltration of a local anesthetic into subcutaneoustissue which decreases patient discomfort, and allows prolonged localanesthesia.

BRIEF SUMMARY OF THE INVENTION

An infiltration cannula and method of using the infiltration cannuladuring an infiltration procedure are disclosed herein. The infiltrationcannula includes: a tubular needle and a hub. The tubular needle has aproximal end and a distal end. The tubular needle also has a pluralityof apertures disposed in a pattern about the distal end. The aperturesare configured to infiltrate fluid into the subcutaneous tissue of apatient. The hub is configured to be held by a person performing theinfiltration procedure. The hub has a first end and an opposing secondend. The first end is attached to the proximal end of the tubular needleand the second end includes a connector configured to connect to aninput source for receiving the fluid to be infiltrated into thesubcutaneous tissue of the patient. The fluid flows from the connector,through the hub and into the tubular needle.

The tubular needle may be manufactured of stainless steel or plastic.

The apertures may be arranged in a helical pattern or in a spiralpattern.

The apertures may be distributed over about 33% to about 90% of thedistal end of the tubular needle.

The apertures may be round or oval.

The fluid may be a local anesthetic.

The infiltration procedure may be performed in conjunction with aliposuction procedure.

A method of infiltrating fluid into subcutaneous tissue of a patientusing an infiltration cannula, such as the one described above mayinclude the following steps: (1) inserting an infiltration cannulathrough a patient's skin and into the subcutaneous tissue of the patientat a desired site; (2) receiving fluid from the fluid source via theconnector; (3) transporting the fluid from the connector through the huband into the tubular needle; and (4) ejecting the fluid from the tubularneedle into the subcutaneous tissue of the patient via the apertures.The infiltration cannula used in performing the method includes: aconnector for receiving the fluid from a fluid source, a hub incommunication with the connector and a tubular needle in communicationwith the hub. The tubular needle has a plurality of apertures disposedin a pattern about a distal end. The apertures are configured toinfiltrate the fluid into the subcutaneous the tissue of the patient.

Steps (1)-(4) may be repeated intermittently. The steps may be repeatedat intervals between about eight hours and twelve hours.

After the desired amount of fluid has been infiltrated at a given site,the infiltration cannula is removed.

The infiltration cannula may be inserted at a new site.

Multiple infiltration cannulas (e.g., two) may be used simultaneously.Use of multiple infiltration cannulas prevents disruption of the methodinfiltration process when one infiltration cannula is removed.

BRIEF DESCRIPTION OF THE DRAWINGS

These as well as other features of the present invention will becomemore apparent upon reference to the drawings wherein:

FIG. 1 is a side elevation view of a stainless steel infiltrationcannula shown inserted in subcutaneous tissue shown in partial crosssection;

FIG. 2 is a section view of the infiltration cannula shown in FIG. 1;

FIG. 3 is a side elevation view of a plastic infiltration cannula showninserted in subcutaneous tissue shown in partial cross section;

FIG. 4 is an exploded view of the infiltration cannula shown in FIG. 3;and

FIG. 5 is a flow diagram illustrating an exemplary procedure for usingan infiltration cannula such as the one shown in FIG. 1 or the one shownin FIG. 3.

DETAILED DESCRIPTION OF THE INVENTION

As described in further detail below, the present invention takesadvantage of the tumescent technique in order to provide intermittentinfiltration of local anesthetic. The present invention results in asignificant decrease in patient discomfort due to the elimination of thepiston-like in and out motion of the cannula. Once the cannula is inplace, there is no need to push the cannula through the tissue in orderto deliver the fluid to a wide area. Using the tumescent technique, thetime needed in order to complete the infiltration of a targeted anatomicarea is reduced to nearly half of the time required when usingtraditional prior art cannulas. The device and method described hereincan use multiple (e.g., two) infiltration cannulas simultaneously. Whileone cannula is actively dispersing tumescent fluid into the subcutaneoustissue, the surgeon can reposition a second infiltration cannula. Thisallows the infiltration process to proceed without interruption, whereasprior art techniques of infiltration must be ceased each time thecannula is withdrawn from the skin and re-inserted into anotherdirection.

The tumescent technique was discovered by Jeffrey Alan Klein, M.D. (theapplicant) in 1985. Dr. Klein first published a description of thetumescent technique in 1987 when he described the use of dilutelidocaine and epinephrine to permit liposuction totally by localanesthesia. A detailed description of the tumescent technique has notbeen published in anesthesiology literature, and therefore, the uniquebenefits of the tumescent technique are not well recognized byanesthesiologists.

The tumescent technique is a drug delivery system that takes advantageof a recently discovered reservoir effect of injecting a relativelylarge volume of relatively dilute solution of a drug into thesubcutaneous tissue.

The present invention takes advantage of the tumescent reservoirphenomenon. It has many novel applications, an example of which is painmanagement. This technique eliminates the need for a continuousinfiltration of local anesthetic and allows for intermittent injections.In exemplary embodiments, the intermittent injections are administeredevery eight to twelve hours.

With the tumescent technique, a large volume of dilute solution of localanesthesia and epinephrine is injected into the subcutaneous spaceresulting in a large bolus (or reservoir) of solution. The profoundvasoconstrictive effect (shrinking of the capillaries) of the diluteepinephrine produces a dramatic delay in the systemic absorption of thelocal anesthetic, which prolongs the anesthetic effects of tumescentanesthesia for eight to sixteen times longer than traditionaltechniques.

Referring now to the drawings wherein the showings are for purposes ofillustrating preferred embodiments of the present invention only, andnot for purposes of limiting the same, FIGS. 1 and 2 illustrate astainless steel (reusable) infiltration cannula 10 and FIGS. 3-4illustrate a (single use) plastic infiltration cannula 30. The cannula10, 30 can be inserted under the skin 52 and into the subcutaneoustissue 50 and tumescent local anesthesia can be infiltrated once everyeight to twelve hours.

Stainless steel infiltration cannulas 10, such as the one shown in FIGS.1 and 2, are precision high quality and reusable. These cannulas can beused to provide tumescent local anesthesia for surgical procedures, suchas liposuction, which require tumescent local anesthesia over arelatively large area.

The cannula 10 includes a tubular needle portion 12 which has a proximalend 14 and a distal end 16. The proximal end 14 of the tubular needle 12is attached to a hub 20 that is used by the anesthesiologist or surgeonto hold the cannula 10 during the infiltration procedure. The hub 20 isconnected to the tubular needle 12 at a first end 22 and has a connector24, such as a luer lock, at an opposing second end. The connector 24 isconnected to a fluid source, such as tubing connected to an IV bag.Fluid enters the cannula 10 via the connector 24.

In exemplary embodiments, the tip at the distal end 16 is closed. Thelocal anesthetic is infiltrated into the patient via apertures 18located proximate the distal end 16 of the tubular needle 12 of thecannula 10. In exemplary embodiments, the apertures 18 are disposedalong the distal end 16 of the cannula 10 in a spiral or helical patternand are distributed over the distal 33% to 90% of the tubular needle 12of the cannula 10. For example, if the length of the tubular needle D is15 cm and the apertures 18 at the distal end 16 cover a length d1 of 5cm, the pattern of apertures of the cannula 10 are distributed over 33%of the tubular needle 12 of the cannula 10.

The proximal portion 14 of the cannula 10 is devoid of apertures, inorder to prevent fluid from leaking out of the cannula insertion site inthe skin.

Plastic infiltration cannulas 30, such as the one shown in FIGS. 3 and4, are single use cannulas and can be used in one of several uniqueways. First, an anesthesiologist or surgeon can insert an infiltrationcannula 30 with stylet 46 into the subcutaneous tissue 50, remove thestylet 46, then attach an IV tubing to the infiltrator and injecttumescent local anesthesia into the targeted area without subsequentrepositioning of the infiltration cannula 30. The plastic flexiblenature of the tubular needle 32 of the disposable plastic cannula 30allows the patient to move or change position of the body without riskof injury that might result if a patient moves while a rigid steelcannula is inserted.

Preferably, the stylet 46 is metal, e.g., stainless steel. The plasticcannula 30 can be blunt-tipped with the metal stylet tip 48 covered bythe rounded tip 39 of the plastic cannula 30. Alternatively, the plasticcannula 30 can be open-ended with the stylet 46 extending a shortdistance past the end 39 of the plastic cannula. 30. In the case of anopen-ended cannula, the metal stylet 46 can be either blunt-tipped(requiring a skin incision to permit insertion into the subcutaneousspace), or sharp-tipped (permitting the cannula to be inserted directlythrough the skin and into the subcutaneous space without requiring apreparatory skin incision.

The plastic cannula shown in FIGS. 3 and 4 is similar to an IV catheterexcept the sharp hollow stylet used for the insertion of an IV catheteris replaced by a solid obturator/stylet 46 that can be either sharp orblunt tipped. Except for the removable stylet 46, the plastic cannula 30is similar to the stainless steel cannula 10 shown in FIGS. 1 and 2 anddescribed above. The plastic cannula 30 includes a flexible tubularneedle 32 having a proximal end 34 and a distal end 36. The distal endhas apertures 38 and the proximal end 34 is devoid of apertures. Asstated above, in exemplary embodiments, the pattern of apertures 38 inthe cannula 30 are distributed over the distal 33% to 90% of the tubularneedle 32 of the cannula 30. For example, if the tubular needle 32 ofcannula 30 shown in FIGS. 3 and 4 has a length D of 15 cm and thepattern of apertures are distributed over a length d1 of 13.5 cm, thenthe apertures 38 are distributed over 90% of the cannula.

A typical infiltration cannula 10, 30 might be 20, 18, 16 or 14 gauge(i.e., 20, 18, 16 or 14 cm in length) with small apertures 18, 38 placedevery 5 mm d2 along the cannula in a spiral or helical pattern. It willbe appreciated that the dimensions used herein are exemplary and thatthe cannula dimensions, range of gauge, relative size shape and patternof apertures can vary greatly depending upon clinical preference.

The proximal end 34 of the tubular needle 32 shown in FIGS. 3 and 4 isattached to a hub 40 that is used by the anesthesiologist or surgeon tohold the cannula 30 during the infiltration procedure. The hub 40 isconnected to the tubular needle 32 at a first end 42 and has a connector44 at an opposing second end. The connector 44 is connected to a fluidsource. As described above and shown in FIG. 4, the stylet 46 can beinserted and removed from the cannula 30.

Infiltration using a plastic infiltration cannula 30, such as the oneshown in FIGS. 3 and 4, can be accomplished using an infiltration pump.Alternatively, the force of gravity could be used to push the tumescentfluid into the tissues by hanging a reservoir plastic bag of tumescentlocal anesthesia (or other dilute drug, such as a chemotherapeutic agentor antibiotics) on an IV pole and connecting bag to the infiltrationcannula by an IV line.

Another application is the injection of tumescent local anesthesia intoa localized area through which a surgeon plans to make a surgicalincision. The effects of vasoconstriction within the tumesced tissueminimizes surgical bleeding. The effects of tumescent local anesthesiaproduce prolonged post operative analgesia and also reduce the risk ofsurgical wound infections.

Yet another application is to provide an easily accessible route forsystemic administration of crystalloid fluids/electrolytes for systemichydration or for other types of drug therapy. Potential clinicalapplications include emergency resuscitation with systemic fluids insituations where insertion of an IV catheter into a vein cannot bereadily achieved. Examples of situations where emergency access forintravenous delivery of fluids might not be possible include acutetrauma or burn wound in civilian or military situations. Anotherapplication might be the emergency treatment of dehydration associatedwith prolonged vomiting or diarrhea (e.g., epidemic cholera) such asamong pediatric patients in rural (e.g., third world) settings. Asubcutaneous infiltration catheter can easily be placed by a layman,whereas inserting an IV catheter into a patient that is severelydehydrated can be difficult even for a skilled physician. Delivery ofsystemic fluids by subcutaneous infiltration is safer in a zero gravitysituation (for example, the Space Station). The addition of a smallamount of capillary vasodilator (e.g., methylnicotinamide) to thesubcutaneous fluid can be used to accelerate the systemic absorption ofthe fluid or drug into the intravascular space.

The cannula 10, 30 is intended to be inserted far enough through theskin 52 so that all of the apertures 18, 38 are within the fat 50 of thepatient. Once the cannula 10, 30 is properly positioned, it can remainstationary while the local anesthetic (or other pharmaceutical) solutionis injected.

After one portion of the targeted area has been tumesced, theinfiltration is briefly terminated (either by turning off the pump or byclamping the IV tubing) while the cannula 10, 30 is repositioned intoanother area of the subcutaneous tissue. The infiltration is thenrestarted with the cannula stationary in its new position.

The infiltrator 10, 30 can also be used in the traditional mode wherebythe cannula 10, 30 is moved through the targeted tissue while the fluidis simultaneously pumped through the cannula 10, 30 and into thesubcutaneous tissue 50.

Another unique aspect of the tumescent technique's reservoir effect isthat one can conveniently achieve a long slow steady absorption of adrug delivered to the subcutaneous space 50 using periodic injections ofa tumescent solution. In certain situations, using a slow IV infusion,the alternative technique, can achieve a slow systemic absorption of adrug but may be difficult, require greater clinical expertise, be moreexpensive, and therefore, less practical than the technique describedherein.

FIG. 5 is a flow diagram illustrating steps performed in an exemplaryinfiltration procedure using a cannula 10, 30 such as the one shown inFIGS. 1 and 2 or the one shown in FIGS. 3 and 4, respectively. Theprocedure begins by inserting the tubular needle 12, 32 of theinfiltration cannula 10, 30 into a desired subcutaneous tissue site 50,e.g., via an incision in the patient's skin 52 (block 100). Fluid isthen transported from the fluid source (e.g., an IV bag) into thecannula 10, 30 via the connector 24, 44 that is connected to the fluidsource. The fluid is transported from the connector 24, 44 through thehub 20, 40 and into the tubular needle 12, 32 (block 102). The fluid isthen ejected from the cannula 10, 30 into the subcutaneous tissue 50 ofthe patient via the apertures 18, 38 at the distal end 16, 36 of thetubular needle 12, 34 of the cannula 10. 30 (block 104).

The fluid is transported (block 102) and ejected (block 104) untilinfiltration at the current site is completed (yes in decision block106). The fluid can be injected into multiple sites in order todistribute the solution over a greater area.

Infiltration at a particular site may be deemed complete upon emptyingof the fluid source or based on the anesthesiologist or surgeon'sdecision to stop the infiltration at the current site. After one portionof the targeted area has been tumesced, the infiltration can be brieflyterminated (either by turning off the pump or by clamping the IV tubing)while the cannula 10, 30 is repositioned into another area of thesubcutaneous tissue. The infiltration is then restarted with the cannulastationary in its new position. If the infiltration at a site iscomplete (yes in decision block 106), the cannula is removed from thecurrent site (block 108). If the infiltration at the current site is notcomplete (no in decision block 106), fluid is transported from the fluidsource (block 102) and ejected into the subcutaneous tissue (block 104)until infiltration at the site is complete (yes in decision block 106).

If infiltration is complete at the current site (yes in decision block106) but infiltration is not complete (no in decision block 110), thetubular needle 12, 32 of the infiltration cannula 10, 30 is insertedinto a new area of subcutaneous tissue 50. The process described aboveis performed until the infiltration process is complete (yes in decisionblock 110). This process can be repeated intermittently, for exampleevery eight to twelve hours as described above.

As described above, multiple infiltration cannulas (e.g., can be used atonce). Thus, a second cannula can be inserted (block 100) at the sametime as a first cannula is being removed (block 108). Thus, theinfiltration process need not be interrupted in order to reposition asingle cannula.

Additional modifications and improvements of the present invention mayalso be apparent to those of ordinary skill in the art. Thus, theparticular combination of parts described and illustrated herein isintended to represent only a certain embodiment of the presentinvention, and is not intended to serve as a limitation of alternativedevices within the spirit and scope of the invention.

1. An infiltration cannula for use in an infiltration procedure, theinfiltration cannula comprising: a tubular needle having a plurality ofapertures disposed in a pattern and distributed over a distal 33% ormore of the tubular needle, the apertures being configured to infiltratea multi liter amount of fluid into subcutaneous tissue of a patient, aproximal portion of the tubular needle being devoid of apertures toprevent leakage or the fluid from the needle to outside of a patient; ahub configured to be held by a person performing the infiltrationprocedure, the hub having a first end and an opposing second end, thefirst end being attached to the proximal end of the tubular needle, thesecond end comprising a connector for receiving the fluid to beinfiltrated into the subcutaneous tissue of the patient, the connectorbeing in fluid communication with the hub and the tubular needle; and acontinuous flow liquid pump connectable to the connector of the hub andoperative to continuously deliver a multi liter amount of the fluidthrough the hub and the tubular needle.
 2. The infiltration cannula ofclaim 1 wherein the infiltration pump is a peristaltic pump.
 3. Theinfiltration cannula of claim 1 wherein the infiltration procedure isperformed in conjunction with a liposuction procedure.
 4. Aninfiltration cannula for use in an infiltration procedure, theinfiltration cannula comprising: a single tubular needle having aplurality of apertures: disposed in a pattern and distributed over adistal 33% or more of the tubular needle, each of the plurality ofapertures being about equal in size to the other apertures of theplurality of apertures, the apertures being configured to infiltrate amulti liter amount of fluid into subcutaneous tissue of a patient, aproximal portion of the tubular needle being devoid of apertures toprevent leakage of the fluid from the needle to outside of a patient; ahub configured to be held by a person performing the infiltrationprocedure, the hub having a first end and an opposing second end, thefirst end being attached to the proximal end of the tubular needle, thesecond end comprising a connector for receiving the fluid to beinfiltrated into the subcutaneous tissue of the patient, The connectorbeing in fluid communication with the hub and the tubular needle.